Hard surface materials used primarily for building or construction purposes such as brick, stone, wood, concrete, ceramics, tile, glass, stucco, plaster, gypsum drywall, particle board or chip board, are generally rigid or semi-rigid materials that are frequently exposed to weathering or to water-based cleaners which tend to penetrate and ultimately degrade the materials. They may also be exposed to solvents or oils which tend to stain or otherwise affect their appearance or useful life. Treating agents for such materials should confer both oil and water repellency to the substrate in a single treatment, and should have a suitably long life with outdoor exposure.
The use of fluorochemical copolymers for imparting oil and water repellency to textiles and paper products is known. For example, U.S. Pat. No. 4,147,851 of Raynolds issued Apr. 3, 1979, discloses that copolymers comprising 50% to 85% by weight of a perfluoroaliphatic acrylate/methacrylate monomer and 15% to 50% by weight of dialkylaminoalkyl acrylate/methacrylate monomer or the corresponding amine salt, quaternary or amine oxide monomer are useful in oil and water repellency applications on textiles, leather and paper products. This patent does not teach that such copolymers have desirable properties when applied as a waterborne composition to hard surfaces with outdoor exposure.
However, the use of certain other fluorochemical copolymers for imparting water, oil and stain repellency to hard surfaces is known. Such copolymers include a fluorinated polyester/isocyanate/catalyst composition in a diluting solvent. Use of perfluoropolyethers is known for protection against atmospheric pollutants. An acrylate/fluoroacrylate/silicone or polyethylene wax/water-soluble stabilizer/water-insoluble coalescent agent/water composition is known for use in an anti-soiling treatment of construction materials.
U.S. Pat. No. 4,931,505 issued in 1990 discloses a coating composition comprising (A) a fluorine-containing copolymer with a fluorine content based on fluoroolefin of at least 10% by weight, and (B) a fluorine-containing copolymer of a polyfluorocarbon monomer with a hydrophilic group-containing monomer wherein said hydrophilic group is a member of a group containing, among others, a quaternary ammonium salt and an amine salt. It is said to provide a weather and stain resistant coating layer on surfaces such as metal, glass, and the like, but the coating solutions contain relatively high percentages of flammable volatile solvents, and these coatings can change the appearance of the coated surface by adding an adhering film.
Thus, known compositions for treating hard surfaces can contain volatile solvents which tend to pollute the atmosphere and are increasingly subject to adverse regulations, are flammable, add a coating layer to the substrate which affects its appearance or produce films which can blister or peel away from the substrate.
There is a need for a treatment composition which imparts durable water, oil and stain repellency to hard surfaces with a minimum release of volatile organic solvents. Preferably the treating compositions are soluble or self-dispersible in water for ease of application and cleanup, form coatings which do not change the appearance of the hard surface, and are not subject to blistering or peeling. The present invention provides such a composition.